Seawater Desalination in Rabigh, Saudi Arabia
In the coastal city of Rabigh, Saudi Arabia, the Rabigh Phase IV Seawater Desalination Project, undertaken by Shandong Electric Power Construction No.3 Company of PowerChina, is a significant endeavor. Once operational, it will draw 1.5 million tons of seawater daily through intake pipelines into the pump house.
The seawater then undergoes multiple treatment steps, with reverse osmosis being a core process.
Before entering the reverse osmosis plant, the seawater first passes through a trash rack and a rotary screen in the pump house to intercept debris larger than 5 mm. Subsequently, flocculants and coagulants are added to make suspended solids and colloids in the seawater agglomerate into flocs for easier filtration. Then, it enters a dual – media pressure filter filled with materials like cobblestones, quartz sand, and pumice to further remove insoluble impurities.
A security filter with a 5 – micron – gap filter element is used to protect the reverse osmosis membranes.
The reverse osmosis system pressurizes the pretreated seawater and processes it through a two – stage reverse osmosis system to ensure the final product water meets the salt content standard. By innovatively installing plugs in the product water pipes of the third and fourth membranes in each membrane housing and directly sending the low – salt product water from the first three membranes to the second – stage reverse osmosis system, the project has reduced the additional pressurization demand and significantly cut energy consumption.
The power consumption per ton of product water has been reduced to the industry’s lowest level of 2.773 kWh, enabling the production of 600,000 tons of clean domestic water daily, benefiting numerous households.